Method and apparatus for determination of moisture in solid materials



I L. E. McALLISTER. I

METHOD AND APPARATUS FOR DETERMINATION OF MOISTURE IN SOLID MATERIALS.

APPLICATION FILED MAY 8, I9l9.

Patented July 20, 1920.

3 SHEEIS-SHEEI I.

L. E EficALLISTER.

METHOD AND APPARATUS FOR DETEBWNATION 0F MOISTURE IN SOLID MATERIALS.APPLICATION FILED MAY 8. 1919.

1,347,106. n d ly 2%, 1920.

3 SHEElS-SHEEI 2.

R QZ/ DEGREES f7 4 6 6 7 6 12 PE CE/VT MOfSTZ/ZZE avwentoz Z-KW L. E.McALLISTER. METHOD AND APPARATUS FOR DETERMINATION OF MOISTURE .|N SOLIDMATERIALS.

APPLICATION FILED MAY 8. 1919.

1,347,106. PatentedJuly 20,1920.

3 SHEEIS-SHEET 3.

. residing at Bellaire,

UNITED STATES PATENT OFFICE.

LAWRENCE E. MOALLISTER, 0F BELLAIRE, OHIO.

METHOD AND APPARATUS FOR DETERMINATION OF MOISTIIRE IN SOLID MATERIALS.

Specification of Letters Patent.

Application filed May s, 1919. Serial No. 295,648

To all whom it may concern:

Be it known that I, LAWRENCE E. M0- ALLIs'rnR, a citizen of the UnitedStates, and Ohio, have invented certain new and useful Improvements inMethods and A paratus for' Determination of Moisture-in S hlidMaterials, of which the following is a specification.

The present invention relates to means for and a method fordetermination of moisture in solid materials and more articularly to anapparatus whereby such determinations ma be made accurately and quickly.

eretofore in the determination of moisture in solid materials such ascoal, charcoal and other finely granular materials, the

' procedure has been to weigh as accurately as dpossible a small sampleof the material an place in an oven which may be heated to temperaturessomewhat above the boiling point of water and dry the sample in thisoven, keeping the temperature as nearly uniform as possible, until thesample shows a constant weight. 1

The accuracy of this procedure is in a great many cases questionable,due to the volatility of certain other constituents than moisture andinvolves the use: of more or less expensive apparatus for controllingthe temperature of the ovens and takes considerable time for eachdetermination. The time used in this operation, while depending to agreat extent upon the character of the material, is, nevertheless,seldom less than several hours.

The present invention is designed to overcome a number of diflicultiesconnected with the above method and has among its objects a process andapparatus for making moisture determinations quickly, accurately, andwithout the use of complicated and expensive apparatus.

As the present invention was made particularly to take care of thedeterminatlon of moisture in producing-activated charcoal, the followingdescription will be based upon such determinations, although it wlll beclear that the method and apparatus are not limited to determiningmoisture 1n charcoal, as it ma undoubtedly be used with advantage inetermining the moisture content of any solid material, which will notpack so tightly in the apparatus as to prevent the passage of airthrough a short column thereof.

The invention will e more readily deimbedded scribed and understood byreference to the passage of air longitudinally of the column.

is closed by means The upper end of tube (2) of a tightly fittingstopper (4) provided with two holes through one of which extends athermometer '(5) having the bulb in the column of charcoal. Through theother hole in stopper (4;) extends a pipe (6) provided with valve (7)which opens into the upper end of tube (2) above the surface of thecharcoal and which is connected at its other end to a pipe (8) leadingfroma tube (9) which in the form illustrated is shaped like an ordinarytest tube. The tube (9) has tube (10) leading therefrom near the top.

The tube (9) is also closed at the top by means of a tightly fittingstopper provided with two holes through one of which the pipe (8)extends to a point near the lower end and through the other of which isinserted a thermometer (11) the bulb being also placed near the lowerend of tube (9). Connected with the side tube (10) is a series offlaskzs (12) containing =suitable Patented July 20, 1920.

drying material such as sulfuric acid and provided with the means forstopping entrained acid." This series of flasks may be two or more innumber having. acid in the first one or more and having in the oneadjacent to (9) a material such as glass wool or some similar materialto act as a baflle for entrained acid. The first of the flasks isprovided with an entrance for air such as funnel tube 18 in which, isplaced a filter plug of glass wool or cotton or other suitable materialto remove dirt from the entering air.

Connected to the lower end of tube (3) is a pipe-(13), which leads backto pipe (8) and is provided with a valve (17) while there is also avalve in pipe 8) between the points of connection therewith of pipes(13) and (6), the'valve referred to being numbered (16) on the drawing.By this arrangement it will be readily seen that the portion of pipe (8)containing valve (16) may be 'used as a by-pass.

7 Pipe (8) is in turn connected at (15) with an apparatus for producingvacuum and is also provided with a flowmeter- (14) for determining therate of flow of air through the apparatus.

'In the preferred method of operation the tube (2) is about 2 cm. indiameter and the column of charcoal 10 cm. long, having the bulb. of thethermometer (5) so placed that the center of the bulb is exactly 3 cm.below the top of the column. While these dimensions have been foundsuitable and the curves onthe accompanying charts plotted to accord withthese dimensions, it is obvious that other dimensions may be used andsuitable curves plotted. It is, therefore, to be noted that thesedimensions are given merely.

by way of example and the invention is not limited thereto, although thedescription will proceed as though the apparatus were crease intemperature is indicated by similar to that of the wet and ture.

constructed in this form and operated aecordingly.

The principle of the present apparatus is dry bulb hygrometer, that is,it. depends upon the lowering of the temperatures produced byevaporation of moisture and it is from the difference in temperaturesshown by the two thermometers (5) and (11) when a definite rate of flowof dry air through the apparatus is produced, that the amount ofmoisture in the sample may be calculated.

In the operation of the apparatus a suitable quantity of the sample isplaced in tube (2') in the manner above indicated and suction is appliedthrough the end (15) of pipe (8), valve (16) being closed and valves (7)and (17) open. The'rate of through the apparatus should be accuratelyregulated according to the amount of sample and the dimensions of thecolumn. Using the dimensions above given this rate of flow should be7300 cc. of air per minute.

When the suction is applied to pipe in the manner mentioned, air entersthe inlet (18) at the end of the series of flasks and passing throughthe drying material therein, becomes entirely deprived of its mois-Passing from theflasks it enters the tube (9) and its temperature may beascertained by means of thermometer (11) immediately before it entersthe sample (1). When the air passesthrough sample (1) evaporation ofmoisture is produced and due to the evaporation there is a correspondinglowering of the temperature. This dethermometer (5).

Upon. continued passage of the air The difference will rapidlytemperature or should be, the drop in temperature is an indicationof-the moisture content so that with the two readin the percentage ofmoisture may be rea ily determined. v

The accompanying chart shown in Fig. 2

is based upon the dimensions of tubes and sample herein given and upon.the use of thermometers graduated with a Fahrenheit scale so that withthe two readings of the temperature, of the ture is very readilydetermined.

An example of the methodof using the chart shown in Fig. 2 is asfollows: Assuming that the initial temperature of the sample, which asstated above is preferably room temperature, is say85 F. and that theminlmum temperature reached by the sample on operating the methoddescribed is 67 F.

tures is 18,

T--T:t

Tzinitial temperature. T'zminimum' tzchange in,

sample and the curves and chart in Fig. 2, the percentage of mo1s-.'

between these two temp'era- Looking at the chart we find on the left Ihand margin as ordinate the series of figures indicating the drop intemperature t. Locating the ordinate which corresponds to the particulartemperature change assumed, z'. e. 18, and following thisline'to theright until it intersects the curve marked 85 F., ie. the initialtemperature, we abscissa of this point corresponds to 6.6 per cent.moisture as indicatedalong the lower edge of the chart. These indicatedon Fig. 2 by letters A, D, an

manner: i It was found by a large numbervof experiments that thedropping temperature in samples in this apparatus was not exactlyproportional to the percentage of moisture in the sample, but follows alaw expressed in general by the equation- (a) tzAM The effect of theinitial temperature is two-fold; v1z.,- at high temperatures the findthat the a points are}.

d E. The curves plotted on the chart shown in;

Fig. 2 were calculated in the followingcapacity of the air for nioisture is greater,

perature is hi h, it is evident that more moisture will e given up by.the sample and'more moisture will be taken up- 'by the air before thesaturation point is reached for initial temperature, a seriesof testswere that temperature, giving a drop in temperature of the samplegreatly different than would be Obtained the initial temperature werelower.

In order to determine the effect of the made, varying the temperature asmuch as tion was derived:

possible, and. the following empirical equa- Inthe general exponentialform as, above equation (a)'becomes t= 3 T ;035)M(0.055(T ssy 0.47 whereI A the constant (3 Curve 2 on the chart shown in Fig. 3 gives values ofthe log (3 for different values of T; and

J Curve 1 onthis'same chart gives values of n for different values of T.So, by the use of thefequ-ations and curve equation (1)) may be used forany temperature. This variation in' temperature may be shown encounteredin the operation. The chart shown in Fig. 2 shows different graphicalrepresentations, thus obviating the use of the equation and enabling theoperator to determine the moisture content of a given sample withoutresorting to calculation.

In the operation. of the apparatus and method, it is essential that thesample under treatment be at the same temperature as .ducing a flow ofdry uniform flow ple, determining the change in temperature perature of.the charcoal may rise somewhat; This indicates a leak of atmosphericair-containing a moisture and'is probably caused by condensation orpossibly heat'ab sorption.

It isalso essential shall be efiicient.

Having now described the invention and the preferred method ofpractising the same, it is to be understood that it 1s not limited tothe specific examples herein given as these may be varied withoutdeparting from the spirit of the invention as indicated in theaccompanying claims.

Claims: I

1. Apparatus for determination of the moisture content of solidmaterial, comprising, in series, means for drying air and determiningthe temperature of said dry air, means for containing a sample. ofi thematerial under observation inl such fashion as to permit passage of airthrough the sample', means for determining the change in temperature ofthe sample, means for determining the rate of flow of air through theapparatus, and. means for producing such flow.

that the drying agent content of solid material comprising proairthrough'a confined sample of the material and ascertaining the change intemperature produced in said sample by evaporation of moisture therefromby the passage of the dry air therethrou h.

3. content of solid material comprising confining a sample of thematerial within a suitable vessel, producing a definite and ofdry airthrough the samproduced by evaporation of moisture from the material,and calculating the moisture content from the change in temperature andthe initial temperaure.

LAWRENCE" E. MoALLISTER.

method of determining moisture It ishereby certified that in LettersPatent No. 1,347,106, granted July 20, 1920, upon the application ofLawrence E. McAllister, of Bellaire', Ohio, for an improvement inMethods and Apparatus for Determination of Moisture in Solid Materials,errors appear in the printed specification requiring correction asfollows: Page 3,1ines 28-29, equation, for the expression (0.055(T'58)-+0.47) read M(0.055(T5 8)- +0.47); same page, line 44, after the wordcurve insert a comma; and that the said Letters Patent should be reaiiwith these corrections therein that the same may conform to the recordof the case in the Patent Ofiice.

Signed and sealed this 28th day of September, A; 1)., 1920.

M. H. COULSTON,

Acting Commissioner of Patents.

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